This invention relates to method and apparatus for peeling a covering from an intermediate portion of an insulative, covered cable or electric wire which method and apparatus are suitable .even for a very narrow electric wire and a very thin electric wire.
A process of peeling a covering from an intermediate portion of an insulative, covered electric wire is an important, indispensable one for the manufacture of a wire harness having many joint portions.
There are two conventional intermediate portion-peeling methods, that is, (1) an intermediate portion-shifting method and (2) an intermediate-portion peeling method. In the former method, a covered electric wire is fixed at a portion near one end of a portion (hereinafter referred to as "peeling portion") to be peeled by a clamp, and an annular slit is formed on a covering of the electric wire at the one end of the peeling o portion of the covering by a pair of vertical blades, and then the vertical blades are slid in a direction away from the clamp, i.e. in a direction toward the other end of the peeling portion so as to shift the covering, thereby exposing a conductor on the peeling portion. In the latter method, slits are formed respectively oh a covering of a covered electric wire at opposite ends of a peeling portion by two pairs of vertical blades, and one pair of vertical blades are shifted toward the other pair (or the two pairs of blades are shifted toward the center of the peeling portion), thereby peeling the covering. As an improved arrangement of the latter method, a laser beam, a water jet or fusion by heating is used for removing the peeling portion.
However, none of the conventional methods can be satisfactorily applied to a narrow or thin electric wire and an electric wire of the type in which the strength of bonding between a conductor and a covering is high.
For example, the intermediate portion-shifting method (1) has a drawback that undesired variations in the peeling length occur due to an aging change, and the intermediate portion-peeling method (2) has a drawback that the conductor is liable to be damaged by the movement of the vertical blades Further, in those methods using a laser beam, a water jet or the like, the cost of the apparatus is high.